基于FPGA和DDS的质子同步加速器共振慢引出信号源设计

Design of slow-extraction signal source within proton-synchrotron based on FPGA&DDS

调研了最新质子同步加速器驱动信号源的生成方式及成功案例,提出了基于现场可编程门阵列(Field Programmable Gate Array,FPGA)与数字频率合成器(Direct Digital Synthesizer,DDS)搭建的三阶共振横向引出激励信号发生平台方案,详细阐述了平台硬件架构及软件设计。同时分析了频率合成中的几个关键点,模拟了经1 kHz数字低通滤波后的高斯噪声信号,修整了模拟输出通道的7阶?型巴特沃斯低通滤波器参数。激励平台实现了频率精度高、频率带宽设置灵活的频率信号源。实验数据测试表明,此平台所产生的频率信号能满足加速器慢引出信号源指标需求。

Background： Proton has a higher precision in cancer treatment than traditional X or y radiation because of its Bragg peak feature. Shanghai Institute of Applied Physics is participating in the development of the first proton therapy facility of China. Purpose： Stable and adjustable proton beam extraction is one of the key points of the project. The aim of this work is to design high resolution frequency signal source for slow beam extraction. Methods： A fully digital signal source platform is implemented using FPGA developing board DE2-115 and Direct Digital Synthesizer （DDS） board AD9910/PCBZ. The communication between DE2-115 and AD9910/PCBZ is realized via SPI interface with Verilog HDL programming. Results： High accuracy and flexible frequency signal is obtained through the platform and visualized clearly by oscilloscope and spectrometer, despite a little harmonic. Conclusion： The preliminary results show that scheme design of the project is reasonable and meets the needs of demands although many aspects of the scheme have to be improved further.